1. Technical Field of the Present Invention
The present invention generally relates to voltage driver circuits, and more specifically, to voltage driver circuits that support the ability to select among varying supported voltages for driving.
2. Background of the Present Invention
The electronic industry is in a state of evolution spurred by the recent changes in technology which have allowed greater functionality in smaller devices. This has resulted in the explosion of new found uses for such small devices (e.g. medical, monitoring etc.), as well as greater functionality in increasingly smaller electronic devices.
The evolution has caused electronic devices to become an inseparable part of our society. Consumers are now buying and demanding electronic devices which are smaller, more powerful, and faster at unprecedented rates. These demands are constantly driving the electronic industry to exceed limitations which were previously considered unsurpassable.
One area ripe for improvement is the output driver circuits that are designed into integrated circuits to provide communication with external circuitry via pins. Specifically, technology has advanced in recent times with an increased awareness towards power reduction. As a result of these advancements and to promote advantageous use of inventory, output driver circuits are often required to drive an upper and lower range of voltages to support both new and older technology interfacing. To perform this dual functionality these dual driver circuits typically include separate pre-driver circuitry for each of the supported voltage ranges. An unfortunate side affect of these current designs is that the pre-driver circuitry supporting the lower voltage driving must be designed so as to accept the higher voltage range during non-operation. This unnecessarily makes the lower voltage pre-driver circuitry slow.
It would, therefore, be a distinct advantage to have a dual mode voltage driver that would provide an upper and lower range of voltages without requiring the design of the pre-driver circuitry for the lower voltage to accept the higher voltage. It would be further advantages if this dual mode voltage driver would automatically sense the appropriate voltage level to select for the driving voltage. The present invention provides such a dual mode voltage driver.
The present invention is a method and system for providing a dual voltage driver where the lower voltage predrive circuitry is isolated from the higher voltage of the higher voltage predrive circuitry during operation. The isolation allows the lower voltage predrive circuitry to operate at faster speeds since slower devices that can handle the higher voltage range are not required. In addition, the present invention also uses a automatic sensing circuit to select which predriver should be active based upon the voltage sensed for required operation.